VW T25 flat four engines have
hydraulic lifters or known as "tappets"
They operate on "
zero lash" (
no gap)
As you seem to be unaware of this, better read this...
http://www.ratwell.com/technical/HydraulicLifters.html" onclick="window.open(this.href);return false; it explains them very well.
Do you not have a haynes manual?
mine are set at
1.5 turns in from the rocker touching the valve (ATDC firing stroke) as per the Ratwell link I have given you.
With lack of use or short journies, tappets
bleed down and get noisy, they also get noisy because of
poor oil quality, poor oil pressure, a
weak/worn or broken lifter return spring,
blocked lifter oil hole.
If the rocker arm continues to batter the valve head, over time it will abnormally wear beyond the range of the lifters ability to take up the gap...subsequently poor engine performance will ensue... and the noise will be present until engine death.
AGG 2.0L 8V. (Golf GTi MkIII)